The class of polymers of carbon monoxide and olefin(s) has been known for some time. Brubaker, U.S. Pat. No. 2,495,286, produced such polymers of relatively low carbon monoxide content in the presence of free radical initiators, e.g., peroxy compounds. G.B. 1,081,304 produced similar polymers of higher carbon monoxide content in the presence of alkylphosphine complexes of palladium salts as catalyst. Nozaki extended the reaction to produce linear alternating polymers in the presence of arylphosphine complexes of palladium moieties and certain inert solvents. See, for example, U.S. Pat. No. 3,694,412.
More recently, the class of linear alternating polymers of carbon monoxide and at least one ethylenically unsaturated hydrocarbon has become of greater interest in part because of the greater availability of the polymers. The more recent processes for the production of such polymers, now known as polyketone polymers or polyketones, are illustrated by a number of published European Patent Applications including 121,965, 181,014, 213,671 and 257,663. The processes generally involve a catalyst composition formed from a compound of palladium, cobalt or nickel, the anion of a strong non-hydrohalogenic acid and a bidentate ligand of phosphorous, arsenic, antimony or nitrogen. The scope of the polymerization is extensive but, without wishing to be limited, a preferred catalyst composition has typically been formed from a compound of palladium, the anion of a non-hydrohalogenic acid having a pKa below about 6 and a bidentate ligand of phosphorus. The resulting polyketone polymers are thermoplastic materials of a relatively high molecular weight and are processed by methods conventional for thermoplastics into a variety of shaped articles of established utility.
In the production of the linear alternating polymers, both the rate of polymerization and the molecular weight of the polymer are important from economic considerations. A higher rate of reaction will, of course, produce more polymer per unit time. For many applications of the polyketone polymers the products of higher molecular weight are more useful. Unfortunately, the increased reaction temperatures which facilitate higher reaction rates generally result in polymer product of lower molecular weight. In practice, the reaction temperature is often selected to obtain polymer of the desired molecular weight and whatever reaction rate which results from that reaction temperature must be accepted. It would be of advantage to provide a process for the production of linear alternating polymers of carbon monoxide and at least one ethylenically unsaturated hydrocarbon which proceeds at an acceptable reaction rate but produces polymer product of an acceptable molecular weight.